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Electricity & Magnetism. Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators. Atoms…. Have neutrons , protons , and electrons . Protons are positively charged Electrons are negatively charged. Electrons….
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Electricity & Magnetism Static, Currents, Circuits Magnetic Fields & Electro Magnets Motors & Generators
Atoms… • Have neutrons, protons, and electrons. • Protons are positively charged • Electrons are negatively charged
Electrons… • Are located on the outer edges of atoms…they can be moved. • A concentration of electrons in an atom creates a net negative charge. • If electrons are stripped away, the atom becomes positively charged.
The world is filled with electrical charges: + - + + + - + - - + + + - - - + + - - -
What is this electrical potential called? • Static Electricity - - - - - + + + - - + +
Static Electricity • The build up of an electric charge on the surface of an object. • The charge builds up but does not flow. • Static electricity is potential energy. It does not move. It is stored.
Static Discharge… • Occurs when there is a loss of static electricity due to three possible things: • Friction - rubbing • Conduction – direct contact • Induction – through an electrical field (not direct contact)
Electricity that moves… • Current: The flow of electrons from one place to another. • Measured in amperes (amps) • Kinetic energy
How can we control currents? • With circuits. • Circuit: is a path for the flow of electrons. We use wires.
There are 2 types of currents: • Direct Current (DC) – Where electrons flow in the same direction in a wire.
There are 2 types of currents: • Alternating Current (AC) – electrons flow in different directions in a wire
There are 2 types of circuits: • Series Circuit: the components are lined up along one path. If the circuit is broken, all components turn off.
There are 2 types of circuits: • Parallel Circuit – there are several branching paths to the components. If the circuit is broken at any one branch, only the components on that branch will turn off.
Conductors vs. Insulators • Conductors – material through which electric current flows easily. • Insulators – materials through which electric current cannot move.
Conductors: Metal Water Insulators: Styrofoam Rubber Plastic Paper Examples
What is Resistance? • The opposition to the flow of an electric current, producing heat. • The greater the resistance, the less current gets through. • Good conductors have low resistance. • Measured in ohms.
What Influences Resistance? • Material of wire – aluminum and copper have low resistance • Thickness – the thicker the wire the lower the resistance • Length – shorter wire has lower resistance • Temperature – lower temperature has lower resistance
What is Voltage? • The measure of energy given to the charge flowing in a circuit. • The greater the voltage, the greater the force or “pressure” that drives the charge through the circuit.
Difference b/t Volts and Amps • Example – you could say that… • Amps measure how much water comes out of a hose. • Volts measure how hard the water comes out of a hose.
Ohm’s Law • Resistance = Voltage / Current • Ohms = Volts / Amps
What is an electromagnet? • Electromagnet – a magnet made from a current bearing coil of wire wrapped around an iron or steel core.
What is a generator? • Generator – a machine that changes mechanical energy to electrical energy • Usually use moving magnets to create currents in coils of wire.
What is a motor? • Motor – a device that changes electrical energy to mechanical energy that can do work.